This invention relates generally to diesel locomotives and deals more particularly with an improved control system which operates in a manner to increase the efficiency of the locomotives included in a multiple unit locomotive consist.
A typical locomotive system or consist includes a plurality of diesel locomotives which cooperate to provide the motive power for the train. The locomotives are mechanically coupled and are connected electrically with one another by a plurality of train line wires. One of the locomotives serves as a lead unit which controls the output power of each of the trail units in the system in accordance with the throttle setting of the lead unit. The locomotives normally operate at less than full power since full power is only required under conditions such as when a steep upgrade is encountered. Consequently, the locomotives all have the same throttle setting which is nearly always less than full throttle.
It has been found that maximum efficiency of a diesel locomotive occurs at full throttle or nearly full throttle. However, as indicated previously, the manner in which locomotive systems have been controlled in the past results in all of the locomotives operating at an intermediate or low throttle setting the vast majority of the time. Therefore, the locomotive consist operates at considerably less than peak efficiency. Due in large part to the rapidly increasing costs of diesel fuel, this inefficiency has taken on increased importance in recent years and much effort has been directed at attempting to increase the operating efficiency of multiple unit locomotive consists.
As indicated in U.S. patent application Ser. No. 102,271 which was filed by Rudolph D. Spigarelli on Dec. 10, 1979, now abandoned, the fuel consumption of a locomotive system can be substantially reduced by maintaining some of the locomotives at full throttle and cutting other units back to the throttle one or idle position. For example, instead of operating all six units of a locomotive consist at half power, the same total output power can be attained by operating three of the units at full power and the other three at idle speed. In this fashion, the overall efficiency of the consist is increased and the fuel consumption is decreased since three of the locomotives are operated at the maximum efficiency full throttle position while the other three locomotives are maintained at idle speed.
Although this arrangement can achieve substantial fuel savings, it is not wholly without problems. Perhaps most significantly, the engineer must manually operate the fuel saver device in the proper manner and at the proper times if it is to function effectively. This requires training of the engineers and willingness on their part to give up some of their control over the operation of the locomotive. In actual practice, many engineers resist using the device to the maximum extent, and its effectiveness suffers accordingly. Furthermore, it is necessary to properly set the set-up switches in each locomotive, and considerable inconvenience is involved in physically entering each locomotive for manual setting of the set-up switches. Also, one or more of the switches may be set incorrectly, and the fuel saver device will not operate properly.
The device shown in the aforementioned patent application is capable only of placing each locomotive either in the full throttle position or in the idle position. There is no intermediate throttle setting that can be achieved in the fuel save mode of operation. This can be a significant drawback in situations where the desired train speed cannot be achieved with a given locomotive unit at idle and yet excessive speed results if that locomotive is at full power. It is also common for the train speed to build up above the desired speed before the engineer thinks to activate the fuel saver device. Again, the device does not function in the manner intended and excessive fuel consumption results.
The present invention has as its primary object the provision of an improved control device for a multiple unit locomotive consist which automatically controls the power output of the individual locomotive units in a manner to maintain the consist at maximum operating efficiency. The automatic operation of the device is of great benefit since the possibility of human error and resistance to use of the device is substantially eliminated.
Another object of the invention is to provide a locomotive control device of the character described which accurately maintains the train speed at the desired set speed.
Still another important object of the invention is to provide a control device of the character described which controls the power output of each locomotive in incremental steps. Preferably, the control device operates to selectively reduce the throttle settings of the individual locomotives either to half throttle or to idle speed, thereby allowing the locomotive consist to accurately maintain virtually any set speed. Consequently, the locomotive system speed is more smoothly maintained than if there were no intermediate half power setting in the fuel save mode of operation.
A further object of the invention is to provide a control device of the character described which is well adapted for incorporation into the existing control circuitry of a conventional locomotive and which requires only minor modification of the existing circuitry.
An additional object of the invention is to provide a control device of the character described which uses only a single designated train line wire for transmitting control signals and which is arranged to permit transmission of the signals in both directions along the designated train line wire. In the latter regard, it is an important feature of the invention that the locomotive system can be physically reversed in its direction of movement, as during backing operations, without adversely affecting the control function of the device. The use of a single train line wire is important because the American Association of Railroads has specifically designated only one of the train line wires for use in connection with fuel conservation devices.
A still further object of the invention is to provide a control device of the character described which functions in a manner to automatically designate the lead locomotive unit and to differentiate it from the remaining or trail units. This is accomplished by detecting the position of an air brake cut-off valve which determines the position of a pressure switch and which in any event must be set in the "cut-in" position (pressure switch closed) for the lead unit and in the "cut-out" position (pressure switch open) for each trail unit. Accordingly, no separate operation such as setting of set-up switches is necessary in order to differentiate between the lead and trail units.
Yet another object of the invention is to provide a control device of the character described which senses when the set speed is being approached and acts in response in a manner to avoid significantly "over shooting" or "under shooting" the set speed.
Another object is to automatically determine the number of trail units in the locomotive consist in order to most effectively control the consist.
Still another object of the invention is to provide a control device of the character described wherein the control circuitry is contained within a sturdy control box in order to minimize the possibility of tampering or damage to the components of the circuitry.
Yet another object of the invention is to provide a control device of the character described which is adapted for use in conjunction with conventional tachometer type speed measuring devices of the type in widespread use on diesel locomotives.
Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description.